Arc-lamp.



R. P. MYERS.

ARC LAMP.

APPLICATION FILED JULY 22,1907.

Patented Nov. 3, 1908.

3 SHEETS-SHEET 1.

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R. P. MYERS.

ARC LAMP.

APPLICATION FILED JULY 22, 1907.

Patentd N0v.3, 1908.

3 SHEETS-SHEET 2.

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THE NORRIS PETERS co., wnsnmaranl'. 0. c4

R. P- MYERS;

ARC LAMP. APPLICATION FILED JULY 22, 1907.-

Patented Nov. 3, 1908.

THE NORRIS Farms co., WASHING UNITED STATES PATENT OFFICE.

RICHARD PHILIP MYERS, OF WALTHAMSTOW, ENGLAND.

ABCLAMP.

To all whom it may concern:

Be it known that I, RICHARD PHILIP MYERs, a subject of the King of GreatBritain, residing at Valthamstow, Essex, England, have invented certainnew and useful Improvements in Arc-Lamps, of which the following is aspecification.

This invention relates mainly to are lamps of the kind in which theregulating mechanism for the movable carbon or carbons is controlled bythe thermal. expansion and contraction of a band, strip, wire or thelike of suitable metal through which the current passes. In the arclamps of this kind heretofore suggested, the said band or strip isliable to be damaged or destroyed by excessive currents more especiallyin cases where a number of lamps are run in series on constant potentialmains. Moreover, when these lamps are so run, one lamp of the series mayremain unlighted with its carbons in contact with each other, this beingdue to such lamp requiring a heavier current than the others to operateits mechanism. ow according to the present invention, in order toobviate these disadvantages, means are provided whereby the motion ofthe free end of the expansible band, strip or wire, hereinafter referredto shortly as the strip, controls the operation of a switch whereby thesaid strip is short-circuited when the temperature thereof becomes eX-cessive. This switch moreover, in cases where c. g. one lamp of a serieson a constant potential circuit fails to strike an are when the currentis turned on, prevents the remaining lighted lamps of the series fromincreasing the lengths of their arcs indefinitely to absorb the voltagein excess of what is required by the reduced number of lamps.

By means of the cut-outs above referred to, the current in the circuit(although not in the strips themselves) is maintained at a somewhat highvalue or is slightly increased by reason of the moving together of thecarbons caused by the cooling of the strips when they areshort-circuited, so as to cause the sluggishly acting lamp to strike itsarc, this being done without incurring any risk of destroying the stripson the lighted lamps. The expansible strip is moreover arranged in theform of a simple loop, the ends being secured by means of pins and eyesto a spring-controlled lever and a fixed block or terminalrespectively'and the bend extending round an insulated or insulatingSpecification of Letters Patent.

Application filed. July 22, 1907.

Patented Nov. 3, 1908.

Serial No. 385,065.

pulley which is mounted on an adjustable support so that, after placingthe strip around the pulley and attaching its ends to the lever andterminal, the said strip can be drawn taut by suitably adjusting thesupport of said pulley. By this means, the number of joints in theelectric circuit is reduced to a minimum and the strip can be veryeasily inserted in position and removed.

In the accompanying drawings, Figure l is a side elevation of the lampmechanism, parts being shown in section. Fig. 2 is an elevation of saidmechanism showing the opposite side to that illustrated in Fig. 1. Fig.3 is a detail View drawn to an enlarged scale showing part of themechanism in Fig. 1. Fig. 4% is an underside view of the parts shown inFig. 3. Fig. 5 is a detail View of the brake drum and chain looking fromright to left of Fig. 1 and drawn to an enlarged scale.

Like letters indicate corresponding parts throughout the drawings.

a is the frame of the lamp, which comprises a tubular guide I) for theupper movable carbon holder 0 and an insulated fixed lower carbon holder(Z which is electrically connected by an insulated wire 6 to the insulated terminal f. The upper carbon holder 0 is connected by a flexibleconductor 9 to the periphery of a pulley h rigidly mounted on an arborwhich is rotatably mounted in brackets 70, 70 on the frame a and whichalso bears a fixed pulley m that has secured to its periphery a cord ithaving attached to its lower end a tubular weight 0 sliding on a guidepillar 29. The said arbor is also provided with a fixed brake pulley (1which coacts with a brake chain 1' that is attached at one end forexample, by soldering to a Hat spring 8 mounted on the uppermost disk ofthe frame a and at the other end to one arm t of a lever t, u pivoted ato, '2) on the brackets 7a, This chain preferably takes one turn roundthe pulley Q as shown.

The thermally expansible strip w, which may consist of watch spring, isprovided at its ends with eyes as, 03, one of which engages with a hookor pin y on an insulated terminal 2 mounted on the uppermost disk of thelamp frame, the other eye engaging with a hook or pin 3 on the arm a ofthe lever t, u. The middle part of the strip 10 extends over a pulley 4Lof insulating material, 6. g. porcelain, which is rotatably mounted in afork 5 provided with a screw threaded extension 6 that extends through ahole in the lower frame-disk and coacts with a wing nut 7 whereby thetension of the strip m can be readily adjusted. The strip '20 is thusarranged in two slightly convergent limbs and can be very readilyremoved by slacking the nut 7 and unhooking the eyes m, a: from the pins7 3. The end of the lever-arm a to which the strip to is attachedpreferably made in the form of a circular are substantially concentricwith the pivots o of the lever 1, u, so as to increase the contactsurface of said strip on said arm and to enable the pull of the strip toon the lever f. u, always to take place at substantially the samedistance from the axis 4), a). The lever-arm 25 is acted upon by aspring 8 in such a manner as to keep the strip in in tension. The lowerend of the spring 8 is secured to a sm'ew-threaded bolt extendingthrough a hole in the lower frame-disk and provided with a wing nut 9,so as to enable the tension of the spring to be conveniently adjusted asrequired.

The operation of my improved arc lamp as follows: Assuming the relativetensions of the cold strip '10 and spring 8 to be such that thebrake-chain r releases the pulley Q and allows the upper carbon to reston the lower carbon, when current is supplied to the terminals 7, 2, itfirst heats the strip 10 and causes it to expand, so as to allow thespring 8 to pull down the arm t of the lever t, a. By this means thelower end of the ln'ake-chain r is drawn down and the said chain gripsand turns the pulley Q and its arbor, thereby turning the pulley m inthe direction to separate the carbons and strike the arc, the spring ameanwhile maintaining the tension in the chain 1' and yielding asrequired. As the carbons burn away, the current falls, the strip tocools and contracts, allowing the pulleys to turn in the reversedirection so to bring the carbons together and ultimately allow thepulley q to slip in the loop of chain r. After this, the currentincreases, the strip 10 expands and the above described operations arerepeated. In order to short circuit the strip w when the current becomesexcessive, the insulated terminal 2 is provided with a spring contacttongue 10, the tree end of which during the normal operation of the lampstands at a short distance from the spring s. When the pull on the brake-chain 1' due to the expansion of the strip exceeds a predeterminedamount, the springs will be brought into contact with the tongue 10 andthe strip '10 thereby short-circuited.

An electric contact 11 electrically connected to the terminal 7 isarranged on the side of the tongue 10 remote from the spring a and atashort distance therefrom, By this means, if the strip to should break,the spring 8 is first drawn down into contact with the tongue 10 andthen the tongue is brought into contact with the contact 11 whereuponthe lamp is entirely short-oircuited.

hat I claim is 1. The combination, in an arc lamp, of an insulatedterminal, a thermally expansible metal strip connected at one end tosaid insulated terminal and. arranged in series with the arc,arc-controlling mechanism actuated by said strip, a switch comprisingtwo spring members, electrical connections between the ends of saidstrip and said spring members respectively, a connection between saidarc-controlling mechanism and one of said spring members whereby theswitch is closed to short-circuit said strip independently of the arewhen the arc-controlling mechanism moved beyond a predetermined distancein separating the carbons, and a fixed contact connected to the otherterminal of the lamp and arranged adjacent to the spring member which isconnected to the insulated terminal of the lamp, so that when saidexpansible strip breaks, this spring member will be moved into contactwith said fixed contact, substantially as described.

2. The combination, in an arc lamp, of a thermally-expansible metalstrip arranged in series with the are, adjustable means for maintainingsaid strip in tension, a brakeband connected atone end to saidtensioning means, a spring coacting with the other end of saidbrake-band, a brakenilley coacting with said brake-band, carbon-teed1necln1nism controlled by said brakc- ')ulley, a yielding contactelectrically connected. to one end of said expansible strip at oneterminal of the lamp and arranged adjacent to said spring, an electricalconnection between said spring and the other end of said expansiblestrip, a second stationary contact arranged on the side of said yieldingcontact remote from said spring and connected to the other terminal ofthe lamp.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witncsses.

RICHARD PHILIP M YE t8.

lVitnesses G110. HARRISON, E. SLADE TEMPLETON.

